Paris , France -LRB- CNN -RRB- Joy Monroe , a tourist from Montana , has come to Paris 's Pont des Arts bridge on a mission of love .

To celebrate her marriage of 28 years , she attaches a padlock to the bridge 's rail then throws the key into the river below .

`` Our love is locked forever , '' she says .

It 's an act that 's been repeated thousands of times , barnacling the Pont des Arts with a dense mass of `` love locks . ''

But its popularity is now straining both the bridge and Paris 's relationship with its romantic visitors , prompting a campaign that seeks to outlaw the trend .

American Lisa Anselmo and French-American Lisa Taylor Huff say they co-founded No Love Locks because the padlocks are endangering historic landmarks and have become a threat to safety .

` Vandalism '

`` I understand that this is a modern expression of love and it 's cool , but history should not be compromised , '' says Anselmo .

`` It 's almost painful to watch this vandalism . ''

She and Taylor Huff say the Pont des Arts , built in the 1800s under Napoleon and damaged in a 1979 barge collision , might not survive much longer unless authorities act .

The bridge currently carries about 700,000 locks with an estimated combined weight of 93 metric tons -- roughly the same as 20 elephants standing on a bridge designed for pedestrian traffic .

Sections of fencing have already fallen out under the weight only to be replaced by unsightly wooden panels .

No Love Locks has created a petition that 's collected more than 2,200 signatures .

`` We just want to give back to the city we love and protect its heritage and beauty , '' says Anselmo .

`` One lock is a poem ; hundreds of thousands are a conundrum . ''

Pollution concerns

According to the official Paris website , the padlock trend started in 2008 and was initially seen as charming .

But the practice quickly got out of hand , with padlocks spreading to other bridges and reappearing as quickly as authorities removed them .

There are concerns that the keys thrown in the Seine will add to the river 's existing pollution .

Graffiti , pickpockets and vendors selling cheap padlocks have also become a problem , prompting many locals to avoid the once picturesque promenade .

`` Parisians feel helpless because we do n't want to appear unwelcoming to tourists , '' Anselmo says . `` But people need to understand that what you 're doing is impacting the residents of the city you love . ''

She points out that a lock is an inappropriate symbol for love in France , a country where the main annual holiday celebrates an historic assault on a prison -- the storming of the Bastille .

Olivier Passelecq , the deputy mayor of the Parisian neighborhood that includes the Pont des Arts , agrees that the locks have become invasive .

`` The public has to know that a public monument is not there just for lovers , '' he says .

'' -LSB- The bridge -RSB- has an historical perspective as one of the most beautiful spots in Paris between the French Institute and the Louvre . ''

Both Passelecq and No Love Locks want to find another place for the locks , mirroring similar schemes in Moscow and Rome .

`` Travelers want to leave their mark on Paris -- it 's touching and we understand that , '' Anselmo says .

`` But show love to the history , to the beauty first , and maybe not putting a lock is the most loving thing you can do . ''

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The No Love Locks campaign seeks to outlaw the practice of affixing padlocks to Paris 's historic bridges

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The Pont des Arts bridge is groaning under the weight of 700,000 padlocks and is at risk of collapse , campaigners say

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A petition to ban the locks and move them elsewhere has gained more than 1,700 signatures